* [PATCH] HID: Allow drivers without listeners to remain on the bus
@ 2012-07-17 21:12 David Herrmann
2012-07-17 21:50 ` Henrik Rydberg
0 siblings, 1 reply; 3+ messages in thread
From: David Herrmann @ 2012-07-17 21:12 UTC (permalink / raw)
To: linux-input; +Cc: jkosina, rydberg, David Herrmann
hid-picolcd and hid-wiimote do not allow any of hidinput, hiddev or hidraw
to claim the device but still want to remain on the bus. Hence, if a
driver uses the raw_event callback but no listener claimed the device, we
still leave it on the bus as the driver probably handles everything by
itself.
Under some circumstances (eg., hidinput_connect() fails and raw_event set)
a device may not be left on the bus even though it has no listeners. But
then if hidinput_connect() fails there are bigger issues than a device
that is left unhandled. So we can safely use this heuristic to avoid
adding another flag for special devices like hid-picolcd and hid-wiimote.
This also removes the ugly hack from hid-picolcd as this is no longer
required.
Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
---
Hi Jiri
I posted another patchset that introduced HID_CLAIMED_OTHER to avoid this
heuristic but Henrik convinced me that this trivial check is the cleaner and
less intrusive implementation. If you're interested, the old patchset was here:
http://thread.gmane.org/gmane.linux.kernel.input/25945
Henrik, can you add your signed-off-by as this was your idea?
Thanks
David
drivers/hid/hid-core.c | 8 ++++++--
drivers/hid/hid-picolcd.c | 4 ----
2 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 9cdc74e..83ca3ba 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1373,8 +1373,12 @@ int hid_connect(struct hid_device *hdev, unsigned int connect_mask)
if ((connect_mask & HID_CONNECT_HIDRAW) && !hidraw_connect(hdev))
hdev->claimed |= HID_CLAIMED_HIDRAW;
- if (!hdev->claimed) {
- hid_err(hdev, "claimed by neither input, hiddev nor hidraw\n");
+ /* There are device drivers that do not allow hidinput, hiddev or
+ * hidraw to be connected but still want to remain on the bus. We
+ * require that these devices use the raw_event callback. Otherwise, we
+ * simply remove them from the bus if no listener claimed them. */
+ if (!hdev->claimed && !hdev->driver->raw_event) {
+ hid_err(hdev, "device has no listeners, quitting\n");
return -ENODEV;
}
diff --git a/drivers/hid/hid-picolcd.c b/drivers/hid/hid-picolcd.c
index 45c3433..74c388d 100644
--- a/drivers/hid/hid-picolcd.c
+++ b/drivers/hid/hid-picolcd.c
@@ -2613,11 +2613,7 @@ static int picolcd_probe(struct hid_device *hdev,
goto err_cleanup_data;
}
- /* We don't use hidinput but hid_hw_start() fails if nothing is
- * claimed. So spoof claimed input. */
- hdev->claimed = HID_CLAIMED_INPUT;
error = hid_hw_start(hdev, 0);
- hdev->claimed = 0;
if (error) {
hid_err(hdev, "hardware start failed\n");
goto err_cleanup_data;
--
1.7.11.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] HID: Allow drivers without listeners to remain on the bus
2012-07-17 21:12 [PATCH] HID: Allow drivers without listeners to remain on the bus David Herrmann
@ 2012-07-17 21:50 ` Henrik Rydberg
2012-07-20 7:45 ` Jiri Kosina
0 siblings, 1 reply; 3+ messages in thread
From: Henrik Rydberg @ 2012-07-17 21:50 UTC (permalink / raw)
To: David Herrmann; +Cc: linux-input, jkosina
Hi David,
> hid-picolcd and hid-wiimote do not allow any of hidinput, hiddev or hidraw
> to claim the device but still want to remain on the bus. Hence, if a
> driver uses the raw_event callback but no listener claimed the device, we
> still leave it on the bus as the driver probably handles everything by
> itself.
>
> Under some circumstances (eg., hidinput_connect() fails and raw_event set)
> a device may not be left on the bus even though it has no listeners. But
> then if hidinput_connect() fails there are bigger issues than a device
> that is left unhandled. So we can safely use this heuristic to avoid
> adding another flag for special devices like hid-picolcd and hid-wiimote.
>
> This also removes the ugly hack from hid-picolcd as this is no longer
> required.
>
> Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
> ---
> Hi Jiri
>
> I posted another patchset that introduced HID_CLAIMED_OTHER to avoid this
> heuristic but Henrik convinced me that this trivial check is the cleaner and
> less intrusive implementation. If you're interested, the old patchset was here:
> http://thread.gmane.org/gmane.linux.kernel.input/25945
>
> Henrik, can you add your signed-off-by as this was your idea?
Gladly, but I would like to change the wording slightly, since a driver
with raw_event set is a listener, and we are still bailing out if
there are no listeners at all. The title is thus misleading.
>
> Thanks
> David
>
> drivers/hid/hid-core.c | 8 ++++++--
> drivers/hid/hid-picolcd.c | 4 ----
> 2 files changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index 9cdc74e..83ca3ba 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -1373,8 +1373,12 @@ int hid_connect(struct hid_device *hdev, unsigned int connect_mask)
> if ((connect_mask & HID_CONNECT_HIDRAW) && !hidraw_connect(hdev))
> hdev->claimed |= HID_CLAIMED_HIDRAW;
>
> - if (!hdev->claimed) {
> - hid_err(hdev, "claimed by neither input, hiddev nor hidraw\n");
> + /* There are device drivers that do not allow hidinput, hiddev or
> + * hidraw to be connected but still want to remain on the bus. We
> + * require that these devices use the raw_event callback. Otherwise, we
> + * simply remove them from the bus if no listener claimed them. */
How about "Drivers using raw_event() are not required to connect to anything else"?
> + if (!hdev->claimed && !hdev->driver->raw_event) {
> + hid_err(hdev, "device has no listeners, quitting\n");
> return -ENODEV;
> }
>
> diff --git a/drivers/hid/hid-picolcd.c b/drivers/hid/hid-picolcd.c
> index 45c3433..74c388d 100644
> --- a/drivers/hid/hid-picolcd.c
> +++ b/drivers/hid/hid-picolcd.c
> @@ -2613,11 +2613,7 @@ static int picolcd_probe(struct hid_device *hdev,
> goto err_cleanup_data;
> }
>
> - /* We don't use hidinput but hid_hw_start() fails if nothing is
> - * claimed. So spoof claimed input. */
> - hdev->claimed = HID_CLAIMED_INPUT;
> error = hid_hw_start(hdev, 0);
> - hdev->claimed = 0;
> if (error) {
> hid_err(hdev, "hardware start failed\n");
> goto err_cleanup_data;
> --
> 1.7.11.2
>
Thanks,
Henrik
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] HID: Allow drivers without listeners to remain on the bus
2012-07-17 21:50 ` Henrik Rydberg
@ 2012-07-20 7:45 ` Jiri Kosina
0 siblings, 0 replies; 3+ messages in thread
From: Jiri Kosina @ 2012-07-20 7:45 UTC (permalink / raw)
To: Henrik Rydberg; +Cc: David Herrmann, linux-input
On Tue, 17 Jul 2012, Henrik Rydberg wrote:
> > hid-picolcd and hid-wiimote do not allow any of hidinput, hiddev or hidraw
> > to claim the device but still want to remain on the bus. Hence, if a
> > driver uses the raw_event callback but no listener claimed the device, we
> > still leave it on the bus as the driver probably handles everything by
> > itself.
> >
> > Under some circumstances (eg., hidinput_connect() fails and raw_event set)
> > a device may not be left on the bus even though it has no listeners. But
> > then if hidinput_connect() fails there are bigger issues than a device
> > that is left unhandled. So we can safely use this heuristic to avoid
> > adding another flag for special devices like hid-picolcd and hid-wiimote.
> >
> > This also removes the ugly hack from hid-picolcd as this is no longer
> > required.
> >
> > Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
> > ---
> > Hi Jiri
> >
> > I posted another patchset that introduced HID_CLAIMED_OTHER to avoid this
> > heuristic but Henrik convinced me that this trivial check is the cleaner and
> > less intrusive implementation. If you're interested, the old patchset was here:
> > http://thread.gmane.org/gmane.linux.kernel.input/25945
> >
> > Henrik, can you add your signed-off-by as this was your idea?
>
> Gladly, but I would like to change the wording slightly, since a driver
> with raw_event set is a listener, and we are still bailing out if
> there are no listeners at all. The title is thus misleading.
So could you guys please come up with a revised version of the patch? I
like the aproach much more than the previous one, so would like to queue
it for 3.6 merge window.
Thanks,
--
Jiri Kosina
SUSE Labs
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2012-07-20 7:45 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2012-07-17 21:12 [PATCH] HID: Allow drivers without listeners to remain on the bus David Herrmann
2012-07-17 21:50 ` Henrik Rydberg
2012-07-20 7:45 ` Jiri Kosina
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